It is often desirable to distribute printed sheets in various predetermined ways, for example to form stacks of prints of predetermined content, or to collate such prints into appropriate sets. For example, the pages of a book, or a packet of engineering drawings or maps, may be printed and sorted or collated into the desired book or packet form.
One such application in connection with which this invention will be described involves the distributing of such prints into separate bins of a print-receiving apparatus which is designated herein as a collator, although it may be used for purposes other than what is sometimes thought of as collation.
The above-identified patent application discloses a system in which prints from a printer are conveyed in a series train to an automatic folder which folds each sheet in any of a variety of desired ways, and delivers the folded sheets in sequence into the appropriate bins of a rotating collator. Typically such collator is rotated by a clutch and brake mechanism which advances it one step at a time, so that the open slit-like mouths of the bins move successively into arrested positions for receiving the successive prints. It will be appreciated that if a bin of the collator becomes too full it will not receive additional sheets, and what amounts to a "jam" will be produced if operation is continued.
In the case of ordinary unfolded sheets the problem of predicting over-filling is not so severe, because the thickness and geometry of such a sheet is substantially constant, known, and predictable. However, when some or all of the sheets are folded, and may be folded in different ways and different numbers of times, the problem is much more severe; a few multiply-folded sheets, for example, will clearly fill much more space than many more simple unfolded sheets. Accordingly, mere counting of the sheets is not adequate to determine how much space they will require. Measuring the effective thicknesses of the various packets after they have been folded and before they reach the collator is also a difficult, unreliable and costly procedure.
In distinguishing the various folded sheets from each other, the term "panel" is used herein to describe each overlapping layer in a sheet; that is, a single unfolded sheet contains one panel; a sheet folded once contains two overlapping panels; a sheet folded in half, and then folded in half again, contains four overlapping panels; and so on. In this connection, it is noted that a twice-folded sheet of four overlapping panels, for example, generally is in effect thicker than four single unfolded sheets superimposed on each other. In some cases, different parts of a sheet will be folded a different number of times; for example, a sheet may be folded only along one edge region. In such cases the number of panels in the sheet is considered to be the maximum number of overlapping panels present at any location on the sheet, since this is ordinarily what determines the amount of lateral space which it takes up.
In the apparatus of the copending application referred to above, immediately successive sheets may be folded in widely different ways, so that the problem of avoiding overloading of one or more bins is especially severe.
Accordingly, an object of this invention is to provide a new and useful method and apparatus for distributing sheets into a plurality of bins.
Another object is to provide such method and apparatus suitable for preventing overloading of said bins by said sheets.
A further object is to provide such method and apparatus which is adapted to the distribution of sheets at least some of which are folded.
It is also an object to provide such method and apparatus in which different sheets are differently folded, and overloading of said bins is nevertheless prevented.